Chloroquine enhances gefitinib cytotoxicity in gefitinib-resistant nonsmall cell lung cancer cells
Journal
PLoS ONE
Journal Volume
10
Journal Issue
3
Date Issued
2015
Author(s)
Abstract
Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), including gefitinib, are effective for non-small cell lung cancer (NSCLC) patients with EGFR mutations. However, these patients eventually develop resistance to EGFR-TKI. The goal of the present study was to investigate the involvement of autophagy in gefitinib resistance. We developed gefitinib-resistant cells (PC-9/gef) from PC-9 cells (containing exon 19 deletion EGFR ) after long-term exposure in gefitinib. PC-9/gef cells (B4 and E3) were 200-fold more resistant to gefitinib than PC-9/wt cells. Compared with PC-9/wt cells, both PC-9/gefB4 and PC-9/gefE3 cells demonstrated higher basal LC3-II levels which were inhibited by 3-methyladenine (3-MA, an autophagy inhibitor) and potentiated by chloroquine (CQ, an inhibitor of autophagolysosomes formation), indicating elevated autophagy in PC-9/gef cells. 3-MA and CQ concentration-dependently inhibited cell survival of both PC-9wt and PC-9/gef cells, suggesting that autophagy may be pro-survival. Furthermore, gefitinib increased LC3-II levels and autolysosome formation in both PC-9/wt cells and PC-9/gef cells. In PC-9/wt cells, CQ potentiated the cytotoxicity by low gefitinib (3nM). Moreover, CQ overcame the acquired gefitinib resistance in PC-9/gef cells by enhancing gefitinib-induced cytotoxicity, activation of caspase 3 and poly (ADP-ribose) polymerase cleavage. Using an in vivo model xenografting with PC-9/wt and PC-9/gefB4 cells, oral administration of gefitinib (50 mg/kg) completely inhibited the tumor growth of PC-9/wt but not PC-9/gefB4cells. Combination of CQ (75 mg/kg, i.p.) and gefitinib was more effective than gefitinib alone in reducing the tumor growth of PC-9/gefB4. Our data suggest that inhibition of autophagy may be a therapeutic strategy to overcome acquired resistance of gefitinib in EGFR mutation NSCLC patients. ? 2015 Tang et al.
SDGs
Other Subjects
caspase 3; chloroquine; cremophor; epidermal growth factor receptor; gefitinib; 3-methyladenine; adenine; antineoplastic agent; chloroquine; epidermal growth factor receptor; gefitinib; quinazoline derivative; animal experiment; animal model; animal tissue; antineoplastic activity; Article; autophagy; cancer inhibition; cancer resistance; cell survival; comparative effectiveness; concentration response; controlled study; drug cytotoxicity; drug efficacy; drug inhibition; drug potentiation; enzyme activation; gene mutation; human; human cell; in vitro study; lung cancer cell line; male; mouse; non small cell lung cancer; nonhuman; PC 9 cell line; tumor growth; wild type; analogs and derivatives; Carcinoma, Non-Small-Cell Lung; drug effects; genetics; Lung Neoplasms; pathology; tumor cell line; Adenine; Antineoplastic Agents; Autophagy; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Chloroquine; Humans; Lung Neoplasms; Quinazolines; Receptor, Epidermal Growth Factor
Publisher
Public Library of Science
Type
journal article